Concrete Roads
and Their Construction

100 CONCRETE ROADS serves the back or cart entrances of a numbei' of warehouses and works to and from which the traffic is of the heaviest description, both two and three-horse lorries and also motor-trucks being used, carrying the largest loads that the very flat grades on the water front make possible, and it is also subjected to much turning and twisting traffic from the fact that many of the ware- houses have cart docks, and practically all unloading is done by- backing the lorries and trucks either into such cart clocks or against the kerb. The street was prepared for paving by scarifying the water- bound macadam, excavating to the required depth and preparing and rolling the sub-grade to the required camber to receive a uniform thickness of 8 in. of pavement, with a fall from the crown to the channel of approximately 1 in 36. Two-coat work was adopted, the lower six inches of 7 to 1 concrete and the upper two inches of 3 to 1. The 7 to 1 concrete consisted of five parts of clean beach shingle having a fair propor- tion of sand, two parts of broken basalt between 1 in. and 2| in. gauge, and one part of Portland cement, while the 3 to 1 concrete consisted of 2'25 parts of beach shingle, 0’75 parts of | in. gauge basalt chippings and one part of cement. The top 2 in. was laid immediately after the lower 6 in. had been roughly brought to its proper shape, and while it was quite green, in order to ensure that the whole 8 in. was practically homogeneous. The surface was brought to a proper camber by a straight timber template shod with steel, operated transversely to the longitudinal axis of the street, from the centre to the channel, on screeds of angle iron fixed to bars in the ground, after which it was steel trowelled till it presented a wet, even surface; after setting had commenced it was lightly broomed to remove glazing of any portion of the surface, and when setting had taken place the concrete was covered with bags and kept wet for eight or nine days. It being midsummer, only three weeks were allowed before the road was opened to traffic, and after nine months it was treated with Californian asphalt, brushed on hot and dressed with screened beach shingle. Prior to the application of the asphalt dressing the surface showed slight signs of wear in one or two places where the shingle had not been so good as in the remaining portions, a fact which emphasizes the necessity of using only the best qualities of aggro-